The invention relates generally to rocket motors, and more particularly to a rocket motor that can be used to tow a payload without placing launch personnel in jeopardy and without damaging the payload by means of excessive acceleration forces and burning propulsion gases.
Rocket motors are well known in the art as a propulsion means that pushes its payload as propulsion gas exits the aft end of the rocket motor. However, some payloads must be towed to their destination for proper operation. For example, the U.S. Navy is developing a mine clearing system in which an explosive line charge array is flown/draped over an area of interest and then detonated to clear a path. As the line charge array is towed in the air to its destination, towing forces cause the array to deploy from a packed configuration. A variety of propulsion systems have been considered to date.
Conventional rocket motors are unacceptable for use as a towing propulsion system owing to the large exhaust footprint that exits the motor at ignition exhaust. The exhaust can damage or prematurely detonate the array of line charges at the launch site thereby placing launch personnel and platform in jeopardy as well as jeopardizing the mission. Further, existing rocket motors are complex, expensive, unreliable and/or unable to meet various insensitive munitions requirements.
Another possible propulsion system being considered is the mortar. However, mortars are incapable of meeting safe range stand off requirements without inducing large performance degrading G forces on the towed system components and on the launch platform.
Accordingly, it is an object of the present invention to provide a propulsion system that can be used to tow a payload.
Another object of the present invention is to provide a propulsion system that can be used to safely launch and tow an array of line charges.
Still another object of the present invention is to provide a propulsion system that is simple, inexpensive, easy to build, and meets insensitive munitions requirements.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a rocket motor assembly for towing a payload is provided. A tubular solid propellant grain is defined by exterior surface area and interior surface area. The exterior surface area is inhibited from ignition. A tubular region of a housing encases the propellant grain and the means for inhibiting ignition on the exterior surface area thereof. The housing is further defined by a first end and a second end at either end of the tubular region. The first end defines a plenum having an annular region defined by a diameter larger than that of the tubular region. The first end is provided with a plurality of holes therethrough communicating with the annular region and directed substantially in the direction of the second end of the housing. A burn-inhibiting baffle is fitted in the propellant grain wherein an annular spacing is defined between the baffle and the interior surface area of the propellant grain. An ignition assembly is mounted at the second end of the housing. The ignition assembly is coupled to the interior surface area of the propellant grain so that the propellant grain burns from the inside out upon ignition. Burn gases are exhausted through the holes in the annular region of the first end of the housing.